A dash is a punctuation mark that is similar to a hyphen or minus sign, but differs from both of these symbols primarily in length and function. The most common versions of the dash are the en dash (–) and the em dash (—), named for the length of a typeface's lower-case n and upper-case M respectively.

Usage varies both within English and in other languages, but the usual convention in printed English text is:

Either version may be used to denote a break in a sentence or to set off parenthetical statements (ideally with intradocument consistency). Style and usage guides vary,[1] but often in this function en dashes are used with spaces and em dashes are used without them:[2]

[Em dash:] A flock of sparrows—some of them juveniles—alighted and sang.

[En dash:] A flock of sparrows – some of them juveniles – alighted and sang.

The en dash (but not the em dash) is also used to indicate spans or differentiation, where it may be considered to replace "and" or "to" (but not "to" in the phrase "from … to …"):[3]

The French and Indian War (1754–1763) was fought in western Pennsylvania and along the present US–Canadian border (Edwards, pp. 81–101).

The em dash (but not the en dash) is also used to set off the sources of quotes:

"Seven social sins: politics without principles, wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, and worship without sacrifice." —Mahatma Gandhi

The figure dash(‒) is so named because it is the same width as a digit, at least in fonts with digits of equal width. This is true of most fonts, not only monospaced fonts.

The figure dash is used when a dash must be used within numbers (e.g. phone number 555‒0199). It does not indicate a range, for which the en dash is used; nor does it function as the minus sign, which also uses a separate glyph.

The figure dash is often unavailable; in this case, one may use a hyphen-minus instead. In Unicode, the figure dash is U+2012 (decimal 8210). HTML authors must use the numeric forms &#8210; or &#x2012; to type it unless the file is in Unicode; there is no equivalent character entity.

In TeX, the standard fonts have no figure dash; however, the digits normally all have the same width as the en dash, so an en dash can be substituted when using standard TeX fonts. In XeLaTeX, one could use \char"2012[5] (Linux Libertine font has the figure dash glyph).

The en dash, n dash, n-rule, or "nut" (–) is traditionally half the width of an em dash.[6][7] In modern fonts, the length of the en dash is not standardized, and the en dash is often more than half the width of the em dash.[8] The widths of en and em dashes have also been specified as being equal to those of the upper-case letters N and M respectively,[9][10] and at other times to the widths of the lower-case letters.[8][11]

The en dash is commonly used to indicate a closed range of values—a range with clearly defined and finite upper and lower boundaries—roughly signifying what might otherwise be communicated by the word "through".[12] This may include ranges such as those between dates, times, or numbers.[13][14][15][16] Various style guides restrict this range indication style to only parenthetical or tabular matter, requiring "to" or "through" in running text. Examples of this usage include:

*Other style differences (e.g., APA "p.m." and "pp." vs. AMA "PM" and "pp") are ignored for the purpose of this comparison.

The preference for an en dash instead of a hyphen in ranges is a matter of style preference, not inherent orthographic "correctness"; both are equally "correct", and each is the preferred style in some style guides. For example, APA style uses an en dash in ranges, but AMA style uses a hyphen.

Various style guides (including the Guide for the Use of the International System of Units (SI) and the AMA Manual of Style) recommend that when a number range might be misconstrued as subtraction, the word "to" should be used instead of an en dash. For example, "a voltage of 50 V to 100 V" is preferable to using "a voltage of 50–100 V". Relatedly, in ranges that include negative numbers, "to" is used to avoid ambiguity or awkwardness (for example, "temperatures ranged from −18 °C to −34 °C"). It is also considered poor style (best avoided) to use the en dash in place of the words to or and in phrases that follow the forms from … to … and between … and ….[14][15]

New York–London flight (however, it may be seen that New York to London flight is more appropriate because New York is a single name composed of two valid words; with a dash the phrase is ambiguous and could mean either Flight from New York to London or New flight from York to London,[16] though New York to London flight could actually also mean New flight from York to London)

Among writers who use en dashes in these contexts, a distinction is often made between "simple" attributive compounds (written with a hyphen) and other subtypes (written with an en dash); at least one authority considers name pairs, where the paired elements carry equal weight, as in the Taft–Hartley Act to be "simple",[14] while others consider an en dash appropriate in instances such as this[17][18][19] to represent the parallel relationship, as in the McCain–Feingold bill or Bose–Einstein statistics. However, there is a difference between something named for a parallel/coordinate relationship between two people (for example, Bose and Einstein) and something named for a single person who had a compound surname, which may be written with a hyphen or a space but not an en dash (for example, the Lennard-Jones potential [hyphen] is named after one person, as are Bence Jones proteins and Hughlings Jackson syndrome [space]). Copyeditors use dictionaries (general, medical, biographical, and geographical) to confirm the eponymity (and thus the styling) for specific terms, given that no one can know them all offhand.

The disambiguating value of the en dash in these patterns was illustrated by Strunk and White in The Elements of Style with the following example: when Chattanooga News and Chattanooga Free Press merged, the joint company was inaptly named Chattanooga News-Free Press, which could be interpreted as meaning that their newspapers were news-free.[22]

An exception to the use of en dashes is usually made when prefixing an already hyphenated compound; an en dash is generally avoided as a distraction in this case. Examples of this include:[22]

An en dash can be retained to avoid ambiguity, but whether any ambiguity is plausible is a judgment call. AMA style retains the en dashes in the following examples,[23] but one could argue that some perverseness may be needed to construe the hyphens-only alternative as ambiguous:

As discussed above, the en dash is sometimes recommended instead of a hyphen in compound adjectives where neither part of the adjective modifies the other—that is, when each modifies the noun, as in love–hate relationship. The Chicago Manual of Style (CMOS), however, limits the use of the en dash to two main purposes:

First, use it to indicate ranges of time, money, or other amounts, or in certain other cases where it replaces the word to.

Second, use it in place of a hyphen in a compound adjective when one of the elements of the adjective is an open compound, or when two or more of its elements are compounds, open or hyphenated.[24]

That is, it favors hyphens in instances where some other guides suggest en dashes, the 16th edition explaining that "Chicago's sense of the en dash does not extend to between" to rule out its use in "US-Canadian relations".[24]

In these two uses, en dashes normally do not have spaces around them. An exception is made when avoiding spaces may cause confusion or look odd. For example, compare 12 June – 3 July with 12 June–3 July.[25]

Like em dashes, en dashes can be used instead of colons or pairs of commas that mark off a nested clause or phrase. They can also be used around parenthetical expressions – such as this one – in place of the em dashes preferred by some publishers,[26] particularly where short columns are used, since em dashes can look awkward at the end of a line. (See En dash versus em dash below.) In these situations, en dashes must have a single space on each side.

In most uses of en dashes, such as when used in indicating ranges, they are closed up to the joined words. It is only when en dashes take the role of em dashes – for example, in setting off parenthetical statements such as this one – that they take spaces around them.[27] For more on the choice of em versus en in this context, see En dash versus em dash.

When an en dash is unavailable in a particular character encoding environment—as in the ASCII character set—the are some conventional substitutions. Often two hyphens are the substitute.

Keyboard shortcuts vary by operating system and by application. In TeX, the en dash may normally (depending on the font) be input as a double hyphen-minus (--). In LaTeX you can also use the macro (\textendash). On Mac OS X, most keyboard layouts map an en dash to ⌥ Opt+-. On Microsoft Windows, an en dash may be entered as Alt+0150 (where the digits are typed on the numeric keypad while holding down the Alt key). In Linux (GTK+ v. 2.10+ applications only, see Unicode input), it is entered by holding down Ctrl+Shift and typing U followed by its Unicode code point, 2013, or using the compose key by pressing the compose key, two hyphens, and a period. In Microsoft Word, the standard shortcut is ctrl+number pad hyphen. But in this or any other word processing app, one can also easily create custom shortcuts, such that, for example, ctrl+hyphen keeps the fingers near the home row.

The en dash is sometimes used as a substitute for the minus sign, when the minus sign character is not available, since the en dash is usually the same width as a plus sign. For example, the original 8-bit Macintosh character set had an en dash, useful for the minus sign, years before Unicode with a dedicated minus sign was available. The hyphen-minus is usually too narrow to make a typographically acceptable minus sign. However, the en dash cannot be used for a minus sign in programming languages because the syntax usually requires a hyphen-minus; because programming languages are usually set in a fixed-pitch (monospaced) font face, the hyphen-minus looks acceptable there.

The em dash, m dash, m-rule, or "mutton"[28] (—) is longer than an en dash. The character is called an em dash because it is one em wide, a length that varies depending on the font size. One em is the same length as the font's height (which is typically measured in points). So in 9-point type, an em dash is 9 points wide, while in 24-point type the em dash is 24 points wide. By comparison, the en dash, with its 1-en width, is in most fonts either a half-em wide[29] or the width of an "n".[30]

The em dash is used in several ways—mainly in places where a set of parentheses might otherwise be used or in places where a colon might otherwise be used;[31] it can show an abrupt change in thought or be used where a full stop (period) is too strong and a comma too weak. Em dashes are sometimes used to set off summaries or definitions.[32] Below, the categories of its use are shown with examples.

Written dialogue can sometimes benefit from the first two (commas or dashes) in that the third (parentheses) may not suggest speech cadence to the reader as directly as the first two. But the difference is subtle and may not matter to every writer. In contrast, the third may have a subtle advantage over the first two in expository writing such as scientific writing and technical writing, because speech cadence is irrelevant there and technical readers may appreciate the grouping and nesting of phrases and clauses that brackets (and bracket nests) allow. Again, the subtlety of this distinction makes the choice a minor one.

It may indicate an interpolation stronger than that demarcated by parentheses, as in the following from Nicholson Baker's The Mezzanine. (The degree of difference is subjective.)

"At that age I once stabbed my best friend, Fred, with a pair of pinking shears in the base of the neck, enraged because he had been given the comprehensive sixty-four-crayon Crayola box—including the gold and silver crayons—and would not let me look closely at the box to see how Crayola had stabilized the built-in crayon sharpener under the tiers of crayons."

In a related use, it may visually indicate the shift between speakers when they overlap in speech. For example, the em dash is used this way in Joseph Heller's Catch-22:

He was Cain, Ulysses, the Flying Dutchman; he was Lot in Sodom, Deirdre of the Sorrows, Sweeney in the nightingales among trees. He was the miracle ingredient Z-147. He was—
"Crazy!" Clevinger interrupted, shrieking. "That's what you are! Crazy!"
"—immense. I'm a real, slam-bang, honest-to-goodness, three-fisted humdinger. I'm a bona fide supraman."

Either an ellipsis or an em dash can indicate aposiopesis, the rhetorical device by which a sentence is stopped short not because of interruption, but because the speaker is too emotional to continue, such as Darth Vader's line "I sense something; a presence I've not felt since—" in Star Wars Episode IV: A New Hope.[33] Because the ellipsis is the more common choice, an em dash for this purpose may be ambiguous, as many readers would assume interruption.

Long pause:

In Middle Modern English texts and afterward, em dashes were used to add long pauses (as noted by Joseph Robertson's 1785 An Essay On Punctuation):

Lord Cardinal! if thou think'st on heaven's bliss,
Hold up thy hand, make signal of that hope.—
He dies, and makes no sigh!

This is a quotation dash. It may be distinct from an em dash in its coding (see Horizontal bar). It may be used to indicate turns in a dialog, in which case each dash starts a paragraph.[34] It replaces other quotation marks, and was preferred by authors such as James Joyce:[35]

In Canada, The Canadian Style (A Guide to Writing and Editing), The Oxford Canadian A to Z of Grammar, Spelling & Punctuation, Guide to Canadian English Usage (Second Edition), Editing Canadian English Manual, and the Canadian Oxford Dictionary all specify that an em dash should be set closed when used between words, a word and numeral, or two numerals.

In Australia, the Style manual (For authors, editors and printers, Sixth edition), also specifies that em dashes inserted between words, a word and numeral, or two numerals, should be set closed. A section on the 2-em rule (⸺) also explains that the 2-em can be used to mark an abrupt break in direct or reported speech, but a space is used before the 2-em if a complete word is missing, while no space is used if part of a word exists before the sudden break. Two examples of this are as follows (note that properly typeset 2-em and 3-em dashes should appear as a single dash, but they may show on this page as several em dashes with spaces in between):

I distinctly heard him say, "Go away or I'll—".

It was alleged that D— had been threatened with blackmail.

Monospaced fonts that mimic the look of a typewriter have the same width for all characters. Some of these fonts have em and en dashes that more or less fill the monospaced width they have available. For example, the sequence "hyphen, en dash, em dash, minus" shows as "- – — −" in a monospace font.

When an em dash is unavailable in a particular character encoding environment—as in the ASCII character set—it has usually been approximated as a double (--) or triple (---) hyphen-minus. The two-hyphen em dash proxy is perhaps more common, being a widespread convention in the typewriting era. (It is still described for hard copy manuscript preparation in the Chicago Manual of Style as of the 16th edition, although the manual conveys that typewritten manuscript and copyediting on paper are now dated practices). The three-hyphen em dash proxy was popular with various publishers because the sequence of one, two, or three hyphens could then correspond to the hyphen, en dash, and em dash, respectively.

Because early comic book letterers were not aware of the typographic convention of replacing a typewritten double hyphen with an em dash, the double hyphen became traditional in American comics. This practice has continued despite the development of computer lettering.[36][37]

In Unicode, the em dash is U+2014 (decimal 8212). In HTML, one may use the numeric forms &#8212; or &#x2014;; there is also the HTML entity &mdash;. In TeX, the em dash may normally be input as a triple hyphen-minus (---). On any Mac, most keyboard layouts map an em dash to ⌥ Opt+⇧ Shift+-. On Microsoft Windows, an em dash may be entered as Alt+0151, where the digits are typed on the numeric keypad while holding the Alt key down. It can also be entered into Microsoft Office applications by using the Ctrl+Alt+-. In the X Window System, it may be entered using the compose key by pressing the compose key and three hyphens. In Microsoft Word, the standard shortcut is ctrl+alt+number pad hyphen. But in this or any other word processing app, one can also easily create custom shortcuts, such that, for example, ctrl+alt+hyphen keeps the fingers near the home row.

These comparisons of the hyphen (-), en dash (–), and em dash (—), in various 12-point fonts, illustrate the typical relationship between lengths ("- n – m —"). In some fonts, the en dash is not much longer than the hyphen, and in Lucida Grande, the en dash is actually shorter than the hyphen (making this default Safari browser font typographically nonstandard and potentially confusing[citation needed]).

The en dash is wider than the hyphen but not as wide as the em dash. An em width is defined as the point size of the currently used font, since the M character is not always the width of the point size.[38] In running text, various dash conventions are employed: an em dash—like so—or a spaced em dash — like so — or a spaced en dash – like so – can be seen in contemporary publications.

Various style guides and national varieties of languages prescribe different guidance on dashes. Dashes have been cited as being treated differently in the US and the UK, with the former preferring the use of an em-dash with no additional spacing and the latter preferring a spaced en dash.[26] As examples of the US style, The Chicago Manual of Style and The Publication Manual of the American Psychological Association recommend unspaced em dashes. Style guides outside the US are more variable. For example, the Canadian The Elements of Typographic Style recommends the spaced en dash – like so – and argues that the length and visual magnitude of an em dash "belongs to the padded and corseted aesthetic of Victorian typography."[39] In the United Kingdom, the spaced en dash is the house style for certain major publishers, including the Penguin Group, the Cambridge University Press, and Routledge. But this convention is not universal. The Oxford Guide to Style (2002, section 5.10.10) acknowledges that the spaced en dash is used by "other British publishers" but states that the Oxford University Press—like "most US publishers"—uses the unspaced em dash.

The en dash – always with spaces in running text when, as discussed in this section, indicating a parenthesis or pause – and the spaced em dash both have a certain technical advantage over the unspaced em dash. Most typesetting and word processing expects word spacing to vary to support full justification. Alone among punctuation that marks pauses or logical relations in text, the not spaced em dash disables this for the words it falls between. This can cause uneven spacing in the text, but can be mitigated by the use of thin spaces, hair spaces, or even zero-width spaces on the sides of the em dash. This provides the appearance of a not spaced em dash, but allows the words and dashes to break between lines. The spaced em dash risks introducing excessive separation of words. In full justification, the adjacent spaces may be stretched, and the separation of words further exaggerated. En dashes may also be preferred to em dashes when text is set in narrow columns, such as in newspapers and similar publications, since the en dash is smaller. In such cases, its use is based purely on space considerations and is not necessarily related to other typographical concerns.

On the other hand, a spaced en dash may be ambiguous when it is also used for ranges, for example, in dates or between geographical locations with internal spaces.

U+2015―horizontal bar, also known as a quotation dash, is used to introduce quoted text. This is the standard method of printing dialogue in some languages. The em dash is equally suitable if the quotation dash is unavailable or is contrary to the house style being used.

There is no support in the standard TeX fonts, but one can use \hbox{---}\kern-.5em--- instead, or just use an em dash.

U+2053⁓swung dash resembles a lengthened tilde, and is used to separate alternatives or approximates. In dictionaries, it is frequently used to stand in for the term being defined. A dictionary entry providing an example for the term henceforth might employ the swung dash as follows:

henceforth (adv.) from this time forth; from now on; "⁓ she will be known as Mrs. Wales"

There are several similar, related characters:

U+007E~tilde (see below)

U+02DC˜small tilde (see below)

U+223C∼tilde operator, used in mathematics. Ends not curved as much regular tilde. In TeX and LaTeX, this character can be expressed using the math mode command $\sim$.

U+301C〜wave dash, used in East Asian typography for a variety of purposes, including Japanese punctuation.

A spacing character usually showing a horizontal line below the baseline (i.e. a spacing underscore). It is commonly used within URLs and identifiers in programming languages, where a space-like separation between parts is desired but a real space is not appropriate. As usual for ASCII characters, this character shows a considerable range of glyphic variation; therefore, whether sequences of this character connect depends on the font used.

Used to indicate where a line may break, as in a compound word or between syllables.

¯

¯¯¯¯¯

U+00AF

macron

A horizontal line positioned at cap height usually having the same length as U+005F_low line. It is a spacing character, not to be confused with the diacritic mark "macron". A sequence of such characters is not expected to connect, unlike U+203E‾overline.

Also called "hard hyphen", denotes a hyphen after which no word wrapping may apply. This is the case where the hyphen is part of a trigraph or tetragraph denoting a specific sound (like in the Swiss placename “S-chanf”), or where specific orthographic rules prevent a line break (like in German compounds of single-letter abbreviations and full nouns, as "E-Mail").

U+3161ㅡhangul letter eu or U+1173ᅳhangul jungseong eu are Hangul letters used in Korean to denote the sound [ɯ].

U+301C〜wave dash and U+3030〰wavy dash are wavy lines found in some East Asian character sets. Typographically, they have the width of one CJK character cell (fullwidth form), and follow the direction of the text, being horizontal for horizontal text, and vertical for columnar. They are used as dashes, and occasionally as emphatic variants of the katakana vowel extender mark.

In many languages, such as Polish, the em dash is used as an opening quotation mark. There is no matching closing quotation mark; typically a new paragraph will be started, introduced by a dash, for each turn in the dialog.

Corpus studies indicate that em dashes are more commonly used in Russian than in English.[40] In Russian, the em dash is used for the present copula (meaning "am"/"is"/"are"), which is unpronounced in spoken Russian.

In French, em or en dashes can be used as parentheses, except you can choose between using a second dash as a closing parenthesis, or not using one, simply closing your sentence with a period as you would in English. Dashes are, however, much less common than parentheses.

Typewriters and early computers have traditionally had only a limited character set, often having no key that produces a dash. In consequence, it became common to substitute the nearest available punctuation mark or symbol. Em dashes are often represented in British usage by a single hyphen-minus surrounded by spaces, or in American usage by two hyphen-minuses surrounded by spaces.

Modern computer software typically has support for many more characters and is usually capable of rendering both the en and em dashes correctly—albeit sometimes with an inconvenient input method. Some software, though, may operate in a more limited mode. Some text editors, for example, are restricted to working with a single 8-bit character encoding, and when unencodable characters are entered—for example by pasting from the clipboard—they are often blindly converted to question marks. Sometimes this happens to em and en dashes, even when the 8-bit encoding supports them or when an alternative representation using hyphen-minuses is an option.

Any kind of dash can be used directly in an HTML document, but HTML also lets them be entered using character references. The em dash and the en dash are special in that they can be written using character entity references as &mdash; and &ndash;, respectively.

In GNU/Linux, under recent versions of GTK+, there are various methods of producing these dashes. For em dashes, one may use the compose key followed by three presses of the hyphen character. For en dashes, one may press the compose key followed by two hyphens and a period. For all dashes, one may press and hold ctrl and shift and then press u (and release them all) after which an underlined u appears. Then, type the Unicode number (i.e., 2015) for the appropriate dash and press enter or the space bar. Also, other keys may be remapped to create dashes.

In OS X using the Australian, British, Canadian, French, German, Irish, Irish Extended, Italian, Pro Italian, Russian, US, US Extended, or Welsh keyboard layout, an en dash can be obtained by typing ⌥ Opt+-, while an em dash can be typed with ⌥ Opt+⇧ Shift+-.[41]

In TeX, an em dash (—) is typed as three hyphen‐minuses (---), an en dash (–) as two hyphen‐minuses (--), and a hyphen (‐) as one hyphen‐minus (-). Mathematical minus (−) is signified as $-$ or \(-\).[42]

On Plan 9 systems, an en or em dash may be entered by pressing the Compose key (usually left Alt), followed by typing en or em respectively.

In Microsoft Windows running on a computer whose keyboard includes a numeric keypad, an en or em dash may be typed into most text areas by using their respective Alt code by holding down the Alt key and pressing either Alt+0150 for the en dash or Alt+0151 for the em dash. The numbers must be typed on the numeric keypad with Num Lock enabled. In addition, the Character Map utility included with MS Windows can be used to copy and paste en and em dash characters into most applications—along with accented letters and other non-English language characters. It can normally be found in the System Tools folder, or the Accessories folder on MS Windows Vista. Character Map can also be opened by typing charmap in the run command box.

In Microsoft Word running on a computer whose keyboard has a numeric keypad, an em dash can be typed with Ctrl+Alt+- (on the numeric keypad, with the numeric hyphen usually in the top-right corner), and an en dash can be typed with Ctrl+-. This doesn't work with the hyphen key on the main keyboard (usually between "0" and "="), which has completely different functions. With Microsoft Word's default settings, in both Windows and Macintosh versions, an em dash symbol, which is not always a true em dash from the font, is automatically produced by Autocorrect when two unspaced hyphens are entered between words (as in "word--word"). An en dash, which again, is not always a true en dash from the font, is automatically produced when one or two hyphens surrounded by spaces are entered: ("word - word") or ("word -- word"). This feature can be disabled by customizing Autocorrect. Other dashes, spaces, and special characters are possible, found through the Tools menu. Unassigned symbols, such as the true minus sign, can be assigned keyboard shortcuts through the Insert menu. To determine if the true en or em dash from the font are being used rather than a cross-referenced character from the Symbol font, copy and paste samples of the dashes into a text editor such as Windows Notepad. Using the true dash is important if one ever needs to share documents with other users in other applications or operating systems.

^Garner, B: Modern American Usage, Second Edition, page 657. Oxford University Press, 2003.

^Bryan A. Garner (2001). Legal writing in plain English: a text with exercises. Chicago guides to writing, editing, and publishing (illustrated, reprinted ed.). University of Chicago Press. p. 155. ISBN978-0-226-28418-7. 6.1 Use an en-dash as an equivalent of to (as when showing a span of pages), to express tension or difference, or to denote a pairing in which the elements carry equal weight.

^Lynn Dupré (1998). Bugs in Writing (Revised ed.). Addison Wesley Longman, Inc. p. 221. ISBN978-0-201-37921-1. use en dashes when you have an equal-weighted pair serving as an adjective, such as love–hate relationship.